The present invention relates to a vend door mechanism for a vending machine and more particularly to such a mechanism that is intended to prevent pilferage of product from the vending machine through the vend door area.
Certain types of vending machines, such as packaged snack vending machines which have a large glass front for viewing product stored in a product storage area, utilize a dispensing chamber below the glass and into which product is dropped by anyone of a number of dispensing mechanism designs. Typically such machines have an opening in the bottom of the product storage area through which product is dropped into the dispensing chamber. The dispensing chamber is accessible to a customer through a delivery door in the front of the machine. Such a delivery door is commonly hinged at the top. The customer generally pushes the door open to access any snack that is in the dispensing chamber. As the delivery door is pushed open a mechanism coupled to the door closes an anti-pilferage door over the opening between the product storage area and the dispensing chamber so that a person accessing the chamber cannot reach up into the storage area and remove product that has not been paid for. These mechanisms move the anti-pilferage door quickly so that opening of the delivery door a few degrees completely closes the anti-pilferage door. However, in many such designs there is sufficient clearance between the delivery door and the front of the machine and between the anti-pilferage door and the opening in the storage area when the delivery door is only slightly moved to allow a tool to be inserted and remove product from the storage area. Also, because there is a desire to vend larger and larger product, the opening between the storage area and dispensing chamber needs to be enlarged which, in turn, requires a larger anti-pilferage door and larger dispensing chamber. Thus, the mechanisms of the above described past designs have proven unsatisfactory because of the large size of the door that must be moved rapidly with very little force.
An alternative to such a design is a rotary vend door which as the customer rotates the door to provide access to the delivery chamber the back side of the cylindrical chamber moves to cover the opening between the storage area and the chamber. Such a device is shown, for example, in U.S. Pat. No. 5,375,737, assigned to the same assignee as the present invention. However, with the desire to increase product size to be vended from vending machines the size of the cylindrical rotary vend door must also be increased which provides space, size and weight problems for such designs.